Detective Sgt. Tom Smith

BART police Detective Sgt. Tom Smith died after being accidentally shot Tuesday by a fellow officer. (BART)

The police chief of the Bay Area Rapid Transit told reporters Wednesday that the department officer who accidentally shot and killed a colleague while serving a search warrant is "extremely upset."

BART police Chief Kenton Rainey declined to identify the officer whose weapon discharged Tuesday during a probation search at an apartment complex in the eastern Alameda County bedroom community of Dublin, killing 42-year-old Detective Sgt. Tom Smith.

Rainey confirmed Tuesday that Smith was the first in the department's history to die in the line of duty

Photos: BART officer fatally shot by partner

"He's extremely upset, obviously," Rainey said of the officer whose weapon discharged.

The officer, who was on leave pending an Alameda County Sheriff's Office investigation, had to be interviewed, Rainey added.

He told reporters that he visited the officer Tuesday night and told him "that we would get through this together as an agency."

"We're in shock, disbelief, we're numb," Rainey said of department personnel. "We're grieving and please give us some time."

Smith, a 22-year-veteran of the department, was in charge of detectives at the department.

Rainey said the search at the apartment complex was to recover stolen items, including a laptop computer, that were related to robberies on BART property, according to Alameda County sheriff's Sgt. J.D. Nelson. 

The suspect of the Dublin residence they were searching was already in custody in connection with the robberies, Nelson said.

The officers entered the apartment and the other officer's weapon went off, striking Smith.

The officer who shot Smith is a 10-year-veteran of the force. They were all wearing bullet proof vests.

Smith was taken to a hospital where he died.

Smith lived with his wife -- also a BART officer -- in San Ramon with their 6-year-old daughter.

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